This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This Phase 2 study is a double-blind, placebo-controlled, randomized, multicenter study evaluating the efficacy and safety of 18 months of treatment sith PF-04494700. Participants radomized to 3 treatment groups will receive 20mg, 5mg and placebo capsules respectively. The study will recruit approximately 399 participants that are 50 years or older and diagnosed with mild to moderate AD as will be indicated from MMSE scores of 14-26. The Howard University site will recruit and monitor 15 of the 399 particpants in the study.